Look the comments in the folow code
...
dataset->AddSerie(wxT("0"), values, WXSIZEOF(values));
BarRenderer *barRenderer = new BarRenderer(barType);
wxColour colorGray = wxColour(100,101,110); //GRAY to display in presentation
barRenderer->SetSerieColour(0, &colorGray); // Not working here (auto set the color RED, GREEN, ...)
dataset->SetRenderer(barRenderer);
GRAY to display in presentation and auto set the colors in AddSerie like RED, GREEN...